Absence of ramp could easily reduce the degradation caused by motion and invalidate the model's predictions for uncertainty based on velocity. None of the papers seem to address this point.
Most of the moving Vernier papers (including all the SC Chung and Bedell papers I think) don't temporally ramp their stimulus! Only exception I know is Mechler & Victor who ramped just over 20 ms Mechler, F. & Victor, J. D. (2000). Comparison of thresholds for high-speed drifting vernier and a matched temporal phase-discrimination task. Vision Res, 40(14), 1839-1855.